Plants regenerate much better than do animals--an entire plant can regenerate from a small snip of tissue, whereas the best that animals can do is the occasional amphibian regeneration of a limb or tail. Xu et al. now analyze subcellular dynamics in the root tip of Arabidopsis to understand how regeneration is directed in response to localized cell ablation. Surprisingly, as new tissues are built, establishment of unidirectional flow of the hormone auxin follows, rather than precedes, cell fate specification. A suite of transcription factors that respond early to changes in auxin distribution directs cell fate respecification.